Improvement in blocks for pavements from furnace-slag



F. A. LUCKENBACH. 4Sheets--Sheet1. improvement in Blocks for Pavements from Furnace-Slag.

No. 127,699 Patented]une11,1872.

4 Sheets--Sheet 2a F. A. LUCKENBACH. Improvement in Blocks for Pavements from Furnace-Slag.

Patented Jung11, 1872.

172 We 72 [v 1,

Witness e 4; $49M 4 Sheets-- Sheet3= F. A. LUCKENBACH.

Improvement in Blocks for Pavements from Furnace-Slag. N0. "27,699 I Patented .IuneH, 1872.

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Patented June 11, 1872.

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v z 'i ss'es iM. PHOTU-L/THUG'RAFf/IC m. 11.)! (0580/0/53 PROCESS] UNITED STATES FREDERIO A. LUOKENBAOH, OF NEW YORK, N. Y.

IMPROVEMENT IN BLOCKS FOR PAVEMENTS FROM FURNACE-SLAG.

Specification forming part of Letters Patent No. 127,699, dated June 11, 1872.

To all whom it may concern:

Be it known that I, FREDERIC A. LUcKEN BACH, of the city, county, and State of New York, have inventedcertain Improvements in the Manufacture of Blocks for Street and Roadway Pavements; and I do hereby 'declare that the following is a full and exact description thereof, reference being had to the accompanying drawing making part of this specification.

The purpose of my invention is to utilize, for pavement-blocks, the slag from iron-smelting furnaces, which is produced in immense quantities, and is not merely a nearly-useless material, but which causes a large expenditure to remove out of the way; and by suitable treatment, substantially as hereinafter specified, to render the pavement-blocks made therefrom of unsurpassed strength, durability, and every good and desirable quality, especially where subjected to great and heavy travel. Buildingblocks and other articles may be made from this material by my improvements.

The slag in its natural state is exceedingly brittle and vitreous, and unfit for the purpose to which I apply it. The first object of my invention is to transform this substance into an exceedingly hard, tough, and compacted material, equal or superior in strength, solidity, and durability to the best natural rock; and by my process of treatment it is molded into blocks of uniform size, even surface, and of a shape to bind the courses together when laid, so that one cannot settle below the general surface of all; and spaces are allowed between the courses to fill with gravel, asphaltum, or other material, where foot-hold to prevent slipping is provided. Thus, with a material harder and more durable than stone, all

the roughness and unevenness of stone are avoided, and a pavement as smooth and even as one of wood is produced, and at a reasonable cost. It also has the advantage of not wearing too smooth and slippery, like stone.-

The-transformation of the slag from the vitreous brittle quality which it naturally possesses into the hard and tough substance required is effected by'adding silica and alumina to it in the melted state; this addition of these substances making up for the deficiency thereof naturally existing in the slag;

or, inother words, counteracting the excess of lime therein, derivedfrom the flux used in the smelting.

The process of adding these ingredientssilica and alumina-and of molding and annealing the blocks ready and fit for use is substantially as follows, and by means ,of apparatus, or the equivalents of the essential parts thereof, as represented in the accompanying drawing.

Let A, Figure 1, represent or indicate an iron-smelting furnace. The slag is taken in its liquid state as it runs from the furnace, so that no additional expenditure of heat is requiredforproducing the blocks. As it comes from the furnace it is conveyed through a pipe or conductor, a, made of iron, fire-clay, or any other suitable material, and kept entirely free from moisture, and is poured or conducted therefrom into a suitable ladle, B, prepared to receive it. While the melted slag is flowing from the furnace to the ladle the additional silica and alumina are incorporated with it by suitable means. The device shown in Fig. 1 is convenient. A close box, funnel, or hopper, 0, is arranged in a suitable position above the conductor a and ladle B, so that the materials placed therein will run by gravity therefrom, through a pipe or conductor, b, which conducts them into the slag-conductor a just above where it empties into the ladle, substantially as shown. The flow through this pipe is stopped or regulated by a stop-cock or valve, 0. The silica and alumina are placed in the hopper (1 generally in the form. of sand and clay mixed, the preparation of which may be the same as for common sand in making mortar. The proportions of sand and clay, or of silica and alumina, need not be precise, and may vary without detriment to the quality of the blocks. I generally use them in about equal quantities; and the proportion of this mixture to the slag need not be definite, but may vary considerably-generally from onefourth to one-sixth as much silica and alumina as there is of slag is sufficient. The object is to supply the deficiency of these substances naturally contained in the slag for producing blocks of the right quality and if they are somewhat in excess no injury is done thereto. The silica and alumina should be heated before being incorporated with the slag, in or- '2 mace der not to detract from the fluidity thereof,

and the hotter they are the better. 1' heat them in the hopper O by introducing heat from the furnace A through a pipe, d, as the heat may be spared, from the furnace with out detriment, and thus no additional expense of heat is incurred. The slag, prepared with the addition of the silica and alumina, as above set forth, is then conveyed in the ladle B to a position over the mold or molds into which it is to be poured for casting into blocks. For this purpose a small truck, D, and railway track E, as shown in Figs. 1 and 2, are most convenient. The molds G G are placed in an annealing-oven, H, of any suitable construction,- that represented'showing a furnace, I, below, with flue-apertures ff to conduct the products of combustion upward into and through the oven into the chimney g. The even is close, except holes h h at the top, through which the molds are inserted and withdrawn, and through which the melted slag is poured from the ladle B above, the railway track lying over the oven, so that the ladle on the truck can be brought into exact position over the molds. The molds are to be heated to a temperature a few degrees below ordinary red-heat of cast-iron in the oven before the slag is poured into them. As soon as the molds are filled, one after another, the movable cover of each hole h in the top of the oven is placed thereon, to keep the heat in the oven and prevent the too rapid cooling of the top of the slag in'the molds. The molds are then kept in the oven till all the redness of the heat derived from the slag has disappeared from thaw-generally about five hours. The molds are then taken from the oven, and the mold ed contents removed therefrom and separated into single blocks, as several blocks arev cast together in each mold. The blocks are immediately piled in quantities close together, one upon another, and allowed there to remain and cool'slowly, so that, when cold, they are thoroughly annealed and fit for use.

The molds-are of peculiar construction, substantially asindicated in Figs. 3, 4, and 5, which represent, respectively, a top view, a central vertical section, and a vertical section near one side of a mold as I usually construct it. First, each mold is divided into several compartments, 1 Z, and each compartment molds several blocks together, as indicated by the divisions in Fig. 5, and at m m min Fig. 6, which shows a vertical section through a mold and the molded blocks cast therein. This molding of several blocks together is not merely for economy and convenience of construction of the molds nor for expedition in molding, which are, however, advantages gained; but the main object is to produce a proper an. nealing of the blocks by the slower cooling effected by the large quantity of the slag thus kept in a mass while cooling. And, besides by thus being enabled to bring certain faces of the blocks opposite to each other in the molds, where the cooling is still slower, than at the sides of the molds, those faces or sides of the blocks are more-thoroughly annealed and tougher, and better fit for resisting the wear and abrasion to which they are exposed in the pavement. And by casting two or more blocks, m m m, vertically in each compartment of the mold and lengthwise of the blocks, a similar effect of more thorough and uniform annealing is produced; and greater compactness and solidity are thereby produced from the greater weight and pressure of the column of melted slag poured into each compartment of themold. In order to enable these blocks m m m of each column to be readily and evenly separated, after being taken from the molds, projections an n are made on the inner surfaces of the mold at the proper distances apart, so EtS. to form sharp V-shaped notches or grooves 7 around the periphery of the column, as indicated most clearly in Fig. 6. By using a coldchisel or other suitable instrument a few blows struck in these grooves around the column will readily separate the blocks with a sufiiciently even cleavage. This operation must be per formed as soon as the blocks are taken from the molds. Second, the compartments of the and 4, into which central compartment the slag is first poured from the tapped ladle above, the said compartment having a flaring top, 1', if necessary, to prevent any waste of the slag in filling. From the bottom of this compartment holes 8 s, Fig. 4, open into the molding compartments Z l, through which the slag flows to fill the same 5 thus the slag in its downward flow from the ladle does not interfere with the filling of the mold, nor mingle air with itself so much as otherwise it would. The compartments 1 l of the mold are open at the top for the free escape of the air and gases, and to enable the operator to see when the mold is filled, as desired. The central compartment is so shaped, as indicated in Fig. 3, as to narrow the upper part of the blocks for forming the channels in the pavement between the courses. The mold is made in sections, as shown.

The form of the block for locking the courses together in the pavement may vary. In Fig. 7 is represented one form which Ihave adopted, showing parts of several courses as laid on the road bed. On one side of each block there is a ledge or shoulder, t, facing upward, and on the In order to provide for the takin gup of the blocks in street pavements for any purpose the end or gutter blocks 22 v of each course have no locking shoulders or projections, but have plane sides, as shown in Fig. 9, so that they can first be lifted directly upward from their bed, and then the other blocks of a course can be drawn out lengthwise. The gutter-blocks may have holes or cavities'w 20 cast in their upper side faces, as indicated, to facilitate their withdrawal with a suitable instrument. As the pavement is liable to be taken up in any part it is convenient to have all the gutter blocks with plain sides; and no ill efi'ect arises therefrom, since the gutters are not subject to heavy pressure and wear like the middle of a street.

Fig. 10 shows another form of blocks for locking the courses together. On one side is a semicircular or other equivalent form of projection, t, and in the other side is a groove, u, of corresponding size and shape. The figure shows how the projections and grooves lock the courses together; and Fig. 11 shows how a pavement is laid complete with such blocks. This form makes a pavement that will always remain smooth and even.

A pavement made of the material and in the manner and form above specified, besides being harder and more durable than that made from any kind of stone, as smooth, and even, and regular, and with as good foothold channels as any wooden pavement, and more thoroughlylocked than any other pavement known to me, has another advantage especially over the block stone pavement, by being made of blocks of precisely the same thickness, so that the street bed or foundation can be thoroughly rammed or compressed and made perfectly shapedandevenbeforelayingtheblocks,whereby there is never any tendency afterward to settle unevenly; whereas stone blocks, being of different thicknesses, have to be bolstered up evenly with sand, which cannot, from the nature of the case, be well compressed and uniformly compacted, so that in a short time after laying an uneven surface is inevitable.

What I claim as my invention, and desire v to secure by Letters Patent, is-

1. The composition of iron-furnace slag with additional silica, alumina, or botli for pavement blocks and analogous uses, substantially as herein specified.

2. The method of combining the silica and alumina with the melted slag as the latter is drawn from the furnace, substantially as herein described.

3. In the process of molding and casting pavement blocks from the slag material, the employment of an oven, H, in which the molds are placed and heated before filling, and retained for partial cooling after filling, substantially as and for the purposes herein set forth.

4. The combination and arrangement of the receiving and discharging ladle B, track E, molds G G, and oven H, substantially as described.

5. A mold, G, provided with compartments 1 Z l for casting several blocks at once, arranged substantially as and for the purpose herein set forth. j

6. A mold, G, provided with afilling-eompartment p, communicating at the bottom with the molding-compartments l l, substantially as and for the purpose herein specified.

7. A mold, G, provided with projections an on its inner surfaces, arranged so that two or more blocks may be cast in one and afterward readily separated, substantially as herein specified.

8. The process of compounding, molding, and casting pavement blocks, substantially as herein specified.

9. The improved pavement block, made in the manner substantially as herein described, as an improved article of manufacture.

10. Apavement constructed of blocks made from the materials and in the manner substantially as herein specified.

Specification signed by me this 3d day of May, 1872.

FREDERIO A. LUOKENBAOH.

Witnesses:

EDM. F. BROWN, J. S. BRowN. 

